Enquiry

This story in the Boston Globe amazes me; the lede:

The latest technical advance out of MIT could dramatically change the drudgery of recharging portable devices: An MIT research team has figured out how to wirelessly illuminate an unplugged light bulb from seven feet away.

The reporting is far less technical than I would like to see, and the only explanation I see is that the researchers use “a carefully designed magnetic field to deliver power to such devices from a range of 10 to 15 feet.”

It is of course well known that magnetic fields induce electric current. You may have seen electric toothbrush chargers that can charge through the plastic waterproof casing, requiring no metal-to-metal contact. They work by generating an electromagnetic field through the casing, inducing current flow within the toothbrush to charge its battery.

Maybe I’ll update this as I read more about it. Obvious questions that come to mind:

1. How do you charge efficiently? My understanding is the little inductive charges in toothbrushes aren’t very efficient, which is tolerable because they don’t use much power anyway.
2. How do you prevent major side effects from occurring, either if something comes in between the charger and device, or if the field spreads out farther than desired. A magnetic field powerful enough to transfer substantial amounts of power could really do some damage. You would think any metal object in the vicinity could become electrified, not to mention people with pacemakers.

Pretty amazing technology, if it ever becomes practical.

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